In present telephone networks, alternative routing is used to handle traffic between a call originating exchange node and the destination exchange node. The direct trunks between these nodes are used as a first choice for the establishment of the connection. Should all the direct trunks be occupied, the overflow is routed over one, or more other nodes in tandem. Thus a trunk group between two nodes may handle direct traffic to a destination and some portion of overflow traffic to another destination.
Existing traffic routing systems in telephone networks route traffic without regard to applied tariffs. However, in the case of intercity networks different tariffs are applied for calls to different cities, depending on the distance. Since an overflow connection occupies two, or more trunks in series, it blocks in this way paths for the direct traffic in several trunk groups. It may occur that a low revenue overflow connection has blocked paths for the more profitable direct traffic parcels. This may be especially true during overload situations when the percentage of overflow connections is increased.
The situation may be even more accentuated in the future integrated services networks (ISN), where the tariffs will depend not only on the intercity distances, but also on the type of service provided. Since the present traffic routing systems disregard tariffs, they do not result in maximum revenues.
Another deficiencies of present routing systems is that each node routes traffic without regard to the actual out-of-service and overload status in the entire network. Thus, calls may enter the network even if no free path to the destination exists, relevant equipment is overloaded, or out-of-service. These calls must be released, but have occupied the network for some time without being successful, blocking in this way paths for calls, which could get through. This phenomenon contributes to non-effective traffic, loading the network and resulting in drop of revenues. As mentioned earlier, the presently practiced network management on manual, or semi-automatic basis is too slow for the relatively quick traffic variations. Late interventions may be inadequate, have no effect, or even worsen the situation. The objective of the invention is to eliminate these deficiencies and to provide a traffic control mechanism, which results in maximum revenue traffic routing.